1. Field of the Invention
The present invention relates to inductor components, and more particularly, relates to a ceramic inductor component having an inductor portion formed of a magnetic ceramic body by baking together with electrodes (electrode material) primarily composed of silver (Ag) and a composite component thereof.
2. Description of the Related Art
Recently, inductor components (ceramic inductor components) provided with magnetic ceramic bodies are widely used.
As an example of the ceramic inductor components mentioned above, there are laminated ceramic inductor components.
The laminated ceramic inductor components are generally produced by a step of forming electrodes used as internal conductors by screen printing or the like on magnetic green sheets containing ferrite or the like, a step of laminating, compressing, and baking the magnetic green sheets under predetermined conditions, and a subsequent step of forming external electrodes so as to be connected with the internal conductors. Accordingly, the laminated ceramic inductor components generally have conductors (for example, coil portions) disposed in ferrite-based ceramic magnetic bodies (chips) so as to form inductor portions.
In addition, ceramic inductor components other than the laminated inductor components as described above have, for example, coiled conductors provided on cores, which are formed by disposing and baking conductive materials on the cores composed of ferrite-based ceramics or the like.
When the ceramic inductor component as described above is produced, as a magnetic material used for a magnetic ceramic body, Nixe2x80x94Cuxe2x80x94Zn (nickel-copper-zinconium) ferrite, Nixe2x80x94Cu (nickel-copper) ferrite, Nixe2x80x94Zn (nickel-zirconium) ferrite, or the like is generally used, which can be baked at a relatively low temperature. Such ferrite materials which can be baked at a relatively low temperature are used because an electrode material primarily composed of Ag having high electric conductivity is preferably baked at a low temperature. This electrode material is used for conductors constituting the inductors in order to improve electric properties of ceramic inductor components.
However, there is a problem in that products using Nixe2x80x94Cuxe2x80x94Zn ferrite or Nixe2x80x94Zn ferrite, as a magnetic material constituting ceramic inductors, tend to have considerable variations in the properties and in the proportion defective in manufacturing process, which are caused by small changes of parameters in the production process.
In order to overcome the problems described above, the present invention provides a ceramic inductor component and a composite component having desired properties, excellent stability, and excellent durability.
In order to clarify the reasons for the variations in properties of products and the defective proportion caused by small changes of parameters in manufacturing process for the ceramic inductors using Nixe2x80x94Cuxe2x80x94Zn ferrite, Nixe2x80x94Cu ferrite, or Nixe2x80x94Zn ferrite, the inventors of the present invention conducted various experiments and research. As a result, the inventors discovered that when the sulfur (S), chlorine (Cl) and sodium (Na) are present in predetermined ranges in the ferrite material, the electric properties thereof, i.e., the inductance L and the Q value could be improved. In addition, they found the insulation resistance was increased, which is an index of reliability, and the high insulation resistance lasted over even long periods of time. Through even further intensive research by the inventors of the present invention, the present invention was made.
That is, a ceramic inductor component of the present invention comprises an inductor portion formed by baking a magnetic ceramic body and an electrode primarily composed of silver integrally; wherein the magnetic ceramic body includes one of Nixe2x80x94Cuxe2x80x94Zn ferrite and Nixe2x80x94Cu ferrite, and contents of sulfur, chlorine and sodium in the ferrite are in the range of about 5 to 150 ppm sulfur, about 5 to 150 ppm chlorine and about 5 to 100 ppm sodium.
When a magnetic ceramic body comprising Nixe2x80x94Cuxe2x80x94Zn ferrite or Nixe2x80x94Cu ferrite is used, and when the contents of S, Cl and Na in the ferrite are set to be in the ranges of about 5 to 150 ppm, about 5 to 150 ppm and about 5 to 100 ppm, respectively, a highly reliable ceramic inductor component can be obtained, which is reliably provided with necessary properties and with excellent stability.
The reason the contents of S, Cl and Na are set to be in the ranges described above is that when the content of S or Cl exceeds the range described above, diffusion of Ag contained in the electrode progresses into the magnetic ceramic body, whereby the inductance L and the Q value are significantly decreased, and when the content of S or Cl is below the range described above, the inductance L and the Q value are decreased. In addition, when the content of Na exceeds the range described above, the insulation resistance is decreased in a loading test, and when the content is below the range, the initial insulation resistance will not meet the specification value (log(IR)xe2x89xa79).
The contents of S, Cl and Na in the ferrite are more preferably in the ranges of about 40 to 120 ppm, about 10 to 50 ppm and about 10 to 20 ppm, respectively.
In this connection, S, Cl and Na in the ferrite can be measured using various known methods.
In the ferrite, S is present in the form of S, S compounds, SO4 ions, and the like, Cl is present in the form of FeCl3, FeCl2, NiCl2, and the like, and Na is present in the form of Na2S, Na2SO4, Na2O, NaCl, and the like,
A ceramic inductor component of the present invention comprises an inductor portion formed by baking a magleticceraic body and an electrode (electrode material) primarily composed of silver integrally wherein the magnetic ceramic body comprises one of Nixe2x80x94Cuxe2x80x94Zn ferrite and Nixe2x80x94Cu ferrite, contents of sulfur, chlorine and sodium in the ferrite material before firing are in a range of about 10 to 600 ppm sulfur, about 10 to 600 ppm chlorine, and about 30 to 120 ppm sodium, and contents of sulfur, chlorine and sodium in the ferrite after firing are in a range of about 5 to 150 ppm sulfur, about 5 to 150 ppm chlorine, and about 5 to 100 ppm sodium.
The S, Cl and Na contained in the ferrite are evaporated to some extent in baking; however, when a ferrite before baking, i.e., starting materials for the ferrite, is used which contains S: about 10 to 600 ppm, Cl: about 10 to 600 ppm, and Na: about 30 to 120 ppm, the contents of S, Cl and Na in the ferrite contained in a magnetic ceramic body baked under general conditions can be controlled in the ranges of about 5 to 150 ppm, about 5 to 150 ppm, and about 5 to 100 ppm, respectively. Consequently, a superior ceramic inductor component can be obtained which is reliably provided with necessary properties and with superior reliability. Accordingly, the present invention can be effectively carried out.
The ceramic inductor component of the present invention described above is provided with a laminated coil provided in the magnetic ceramic body, as the inductor portion described above, in which electrode layers are laminated with each other with ceramic magnetic layers provided therebetween and are connected with each other.
In the present invention, the structure of the electrode (conductor) is not specifically limited. However, when the present invention is applied to a ceramic inductor component having a laminated coil, as an inductor portion, formed of magnetic ceramic layers and electrode layers laminated therewith, it is particularly effective, since improvements can be realized in the stability of properties and reliability of the ceramic inductor component (laminated inductor) having a laminated coil which is compact and can yield a large inductance, as an inductor portion.
A composite component of the present invention comprises an inductor portion formed of a magnetic ceramic body by baking together with electrodes (electrode material) primarily composed of Ag and at least another element integrated with the inductor portion, wherein the magnetic ceramic body comprises one of Nixe2x80x94Cuxe2x80x94Zn ferrite and Nixe2x80x94Cu ferrite, and the contents of sulfur, chlorine and sodium in the ferrite are in a range of about 5 to 150 ppm S, about 5 to 150 ppm Cl, and about 5 to 100 ppm Na.
In the composite component having an inductor portion, when Nixe2x80x94Cuxe2x80x94Zn ferrite or Nixe2x80x94Cu ferrite is also used a magnetic ceramic body constituting an inductor portion, and when the contents of S, Cl and Na in the ferrite are set to be in the ranges of about 5 to 150 ppm, about 5 to 150 ppm, and about 5 to 100 ppm, respectively, a highly reliable composite component can be obtained which is reliably provided with necessary properties and with superior stability.
The reason the contents of S, Cl and Na are set to be in the ranges described above is the same reasons as described in the case of the ceramic inductor component described above.
The contents of S, Cl and Na in the ferrite are more preferably in the ranges of about 40 to 120 ppm, about 10 to 50 ppm, and about 10 to 20 ppm, respectively.
In the present invention, at least another element integrated with the inductor portion is the broad concept including a capacitor portion, an inductor portion having properties which is different from the inductor portion described above, a resistor, a varistor, and the like.
A composite component of the present invention comprises an inductor portion formed of a magnetic ceramic body by baking together with electrodes (electrode material) primarily composed of silver, and at least another element integrated with the inductor portion, wherein the magnetic ceramic body comprises one of Nixe2x80x94Cuxe2x80x94Zn ferrite and Nixe2x80x94Cu ferrite, wherein contents of sulfur, chlorine and sodium in the ferrite material before firing are in a range of about 10 to 600 ppm sulfur, about 10 to 600 ppm chlorine, and about 30 to 120 ppm sodium, and contents of sulfur, chlorine and sodium in the ferrite after firing are in a range of about 5 to 150 ppm sulfur, about 5 to 150 ppm chlorine, and about 5 to 100 ppm sodium
When a ferrite before baking, i.e., starting materials for the ferrite, is used which comprises about 10 to 600 ppm S, about 10 to 600 ppm Cl, and about 30 to 120 ppm Na, the contents of S, Cl and Na in the ferrite after baking contained in the magnetic ceramic body can be controlled-in the ranges of about 5 to 150 ppm, about 5 to 150 ppm, and about 5 to 100 ppm, respectively. Consequently, a highly reliable ceramic inductor component can be obtained which is reliably provided with necessary properties and with stability. Accordingly, the present invention can be advantageously carried out.
The composite component of the present invention described above is provided with a laminated coil provided in the magnetic ceramic body, as the inductor portion, in which electrode layers are laminated with each other with ceramic magnetic layers provided therebetween and are connected with each other.
In the present invention, the structure of the electrodes (conductors) is not specifically limited. However, when the present invention is applied to a composite component using a laminated coil, as the inductor portion, formed of magnetic ceramic layers and electrode layers laminated therewith, it is particularly effective, since improvements can be realized in the stability of properties and reliability of the composite component having a laminated coil which is compact and which can yield a large inductance, as an inductor portion.